Harvard-Westlake High School closed two Los Angeles-area campuses Friday because of an Instagram post from the verified account of alumnus and former NFL offensive lineman Jonathan Martin, which featured an image of a shotgun and mentioned the private school by name.

The Los Angeles Times and ABC News reported that Martin was taken into custody; the Times confirmed the Instagram account belonged to Martin.

“The safety of our students, faculty, and staff is always our primary concern,” Harvard-Westlake officials said in a message sent to students Friday morning and obtained by the Times. “So, out of an abundance of caution, we made the decision to close school today. The school’s private security team is working with the Los Angeles Police Department, which is present on both campuses. With these precautions in place, we believe there is no imminent threat to our campuses or our school community.”

Harvard-Westlake president Rick Commons confirmed to The Chronicle, the school’s student online newspaper, that an Instagram post from verified user @jmart led to the decision to close the campuses.

The image — from an Instagram story on Martin’s account — included the message, “When you’re a bully victim & a coward, your options are suicide, or revenge,” according to an image of the post that circulated Friday. The post also included the hashtags #HarvardWestlake and #MiamiDolphins, and tagged the Instagram accounts of Richie Incognito and Mike Pouncey, two of Martin’s former Dolphins teammates, as well as two other individuals.

A second-round pick of the Dolphins out of Stanford in 2012, Martin left the team during the 2013 season amid reports of alleged bullying by Incognito. Martin sat out the remainder of the season and Incognito was suspended by the Dolphins. A subsequent investigation by the NFL found that Incogntio, Pouncey and John Jerry had engaged in harassment directed at Martin, who said he considered suicide.

Phone calls and a text message to Martin from The Washington Post on Friday were not immediately returned.

“I’m a man,” Martin told NBC’s Tony Dungy in January 2014 during his first interview after leaving the Dolphins. “I’m a grown man. I’ve been in locker rooms. There’s vulgar language in locker rooms. One instance doesn’t bother me. It’s the persistence of it. I wish I would have had more tools to solve my situation … but I felt trapped, like I didn’t have a way to make it right. And it came down to the point where, you know, I thought it was best just to remove myself from the situation.”

The Dolphins traded Martin to the 49ers after the 2013 season and he appeared in 15 games for San Francisco in 2014. He retired from the NFL before the 2015 season citing a back injury. Martin, who graduated from Harvard-Westlake in 2008 and was elected into the school’s sports Hall of Fame in 2014, revealed that he felt uncomfortable as a minority at the private school.

“You learn to tone down your size & blackness by becoming shy, introverted, friendly, so you won’t scare the little rich white kids or their parents,” he wrote in a Facebook post from 2015. “Neither black nor white people accept you because they don’t understand you. It takes away from your self-confidence, your self-worth, your sanity.”

Scott AllenScott Allen has written about the Capitals, Nationals, Redskins, Wizards and more for The Washington Post's D.C. Sports Bog since 2014. Before joining The Post, he wrote about high school sports for USA Today, developed courses for a Web-based training company, and worked as a reporter and page designer for the Casper (Wyo.) Star-Tribune. Follow